Jetty



' S. M. WOOD Dec. 10, 1935.

JETTY 4 Original Filed Aug. 20, 1932 w a mm Reisaued Dec. 10, 1935 This invention relates to improvements in 'ietty.

The problem of protecting lake front property is one which has presented innumerable difficulties. On the shores of the Great Lakes, landv slides have occurred from time to time causing the destruction of thousands of dollars worth 0.1 property. The major cause of these landslides, in most sections, is the accumulation of seepage water underneath the ground. This seepage water, which is constantly flowing toward a natand collects for a period of time until the weight of the accumulation overcomes the obstruction. The water will then burst through the hillside causing a cave in of soil above. The only'eflective way of controlling the seeping water is through a suitable drainage system. There is, however, another important factor which contributes with the seepage water in causing a receding shore line, and that is the erosive action of the lake's forces. Necessarily, this erosive action is most damaging during a period when the lake level is high, and in view of the fact that statistics show that high levels occur in regular cycles, there is always a period of transition between a low level and a high level during which most property owners are inadequately protected.

3 Heretofore, it has been attempted to check this erosive action by building retaining walls which parallel the edge of the hillside. There is, however, no wall strong enough to permanently withstand the action of the lake's forces, and this type of protection is therefore eflicacious for a short time only. Along, gradually sloping beach well supplied with sand and gravel. is the best protection against erosive action, as it has the 40 ability to rob a storm of its destructive power, and it is to the formation of a beach of this type that this invention particularly relates. The principal forces causing erosion on a lake shorearecontributed to by the air and by the water itself, and the two movements set up by the air are'wave action and littoral currents. With a wind blowing directly at right angles to the shore, denudation of the beach takes place, as there is a surface drift shoreward and an undertow lakeward, which, assisted by the fact that the waves stir up sediment, is able to convey material from the short out to deeper water.

The most common condition is when the wind Sydney LL Wood, Lake Bluff, Ill.

Original No. 1,928,413, dated Serial No. 629,565, August 2., 1932. for reissue September "i, 1935, Serial No. 89,661

scum. (01. 61-4) rural outlet in the lake, often meets obstructions,

carrying a large amount of soil with it. and

is blowing at an oblique angle'to the short,snd ss'whenthisisthecassthosandandothorpar PATENT OFFICE 28, 1988, Application ticles held insuspensionin the water are caused to travel along the shore line. With this fact in mind, it may be seen that the particles can be accumulated by the construction of an obstacle across their path, that is, by the construc- 5 tion of a Jetty or groin extending into the lake at right angles to the bank. The formation of a suitable type of protective beach by this method, however, cannot be accomplished with the ordinary type of groin, as it is found that while 10 deposits may form on the storm side of the jetty, they will tend to concentrate to provide a relatively steep slope adjacent the Jetty on this side, and on the lee side objectionable scouring will takeplace. It is also found that with most types 15 of Jetties, scouring will take place at the outer end of the jetty due to the accelerated velocity of 'the littoral currents around said end.

It is, therefore, one of the objects of the present invention to provide an improved method of 20 forming protective beaches which results in the formation of a long, gradually sloping beach on both sides of the jetty, and in the elimination of securing action at the outer end.

A further object of the invention is to provide 25 an improved Jetty for effecting. commercial exploitation of the above method.

Other objects of the invention are to provide a Jetty which greatly accelerates the deposit of beach building material, whichnulliiles the wave 30 action and reduces the energy of littoral currents, and which causes the deposit of a greater percentage of fine sand.

A further object of-the invention is to provide a Jetty adapted to produce a beach which is 35 advantageous, not only in that it protects the shore line, but also in that it renders the shore unusually suitable for bathing purposes.

With the above and other objects in view, the invention consists of the art of forming protec- 40 tive beaches, and all its parts and combinations as set forth in the claims, and all equivalents thereof.

In the accompanying drawing illustrating one complete embodiment of the preferred form of 45 the invention, in which the same reference numerals designate the same parts man of the views:

Fig. i is a side elevational view of the im- Proved Jetty; 50

lake shore showing a plurality of parallel jetties installed.

Referring more particularly to the drawing, the

' numeral 5 designates a hillside leading down to With the present invention, in order to obstruct,

the littoral currents to cause the deposit of particles of sand in proper formation to provide a long. gradually sloping beach, one or more jetties'.

must be extended from the hillside or wall I outwardly into the lake at approximately right angles to the hillside. In view of the fact that permeability is unimportant on the portion of the 'beachcloseto the hillside whichisnot reached by the water of the lake, it is preferred to construct the first section of the jetty of concrete or other impermeable material,- asat I. At the outer end of the section I, the construction is continued bytheuseofarockiillorothernllcomposed'of individual elements. These rocks are preferably approximately rectangular in shape and are preferably laid in the manner indicated by cross section in Fig. 2 to provide a jetty with sloping 'sidesl. Therocksarealsosolaidthatthereisa permeability in the wall of approximately 30 per cent produced by spaces ll formed between adjacent corners of the rocks. In the portion of the wall adjacent the section line 2-2 of Pig. 1,

the rocks are preferably laid with a certain degree 'of regularityin the-manner shown lung. 2.

As the jetty extends outwardly into the lake, however, it is very advantageous to increase the permeability. and this feature is one of extreme importance in the present invention. This increasein permeabilityis accomplished by layingthe rocks in less regular formation, as the jetty extends outwardly as indicated in Fig. 3, wherein itmaybeseenthattherocksarelessregularin formandarelaidinamorehaphaaardmanner tocompel the water to pass in an indirect or tortuous course through the wall and to provide largerspaces ll betweent'heindividualrocksfor the purpose of increasing the permeability.

Itmaybeseenthatthemajorportionofthe length of thejetty projects above the water line. At the outer end, however, it is desirable to have apartialmbmergencebelowthewaterlevehas or outward along the sides of prevent scouring at the end and along the sides. I

Itisfoundthatthecharacterofthebe'achmay shcielinetoadirecilowingaroundtheendof currezntsstrikethepei'meablejetty,

thejettywithacceieratedveloci Whenthe littoral currents strike the sides of an impermeable jetty, there is likely to be .a momentary and rather abrupt changein the direction of travel of the currents which causes a deposit in 5 a rather abrupt manner close to the windward side of the jetty, and inasmuch as this deposit will be concentrated adjacent the jetty, any beach developed will have an abrupt siope and will not be desirable. Furthermore, due to the acm celerated velocity of the littoral currents as they move around the end of theimpermeable jetty. the fine sands are carried with the current, and the majority of the fill adjacent the jetty will be of coarser material. In addition, the action of thecurrents around the end of an impermeable jetty wherein the velocity is greatly. accelerated willcauseamarkedscouringtotakeplaceatthe outer end of the jetty, and thereby develop a deep water spot objectionable for bathing purgo poses.

with the present invention, it is to be noted that the major portion of the length of the jetty is permeable, and as a result. while the littoral currents are obstructed in a manner to cause the deposit of sand and ,other material held in suspension, nevertheless, due to the permeable nature of the wall. the water can flow-through the spaces i0 and H so that there is not the tendency for the currents to move in a direction 3 parallel to the jetty and travel around the outer end with accelerated velocity'such as is the case with the jetty of the impermeable type. Thus scouring at the outer end is eliminated. Furthermore, due to the fact that the currents are slowed down in a uniform manner by the permeable jetty and can trickle through an even deposit of fine material is encouraged on both sides of the jetty. and this deposit will gradually build up. notonly directly adjacent the sides, but for a substantial o distance laterally therefrom to cause the formation of a long, gradually sloping beach composed of fine particles of sand. with the impermable type of jetty, the littoral currents which rush aroundthe outer end andtherecause scouring and which then move inwardly toward the shore on the other side of the jetty. will cause a scouring on the lee side.

With the permeable type of jetty wherein the permeability gradually increases from the inner so endtotheouterend,andwhereintheouterend isalsopartiallysubmerged,thepassingofthe water through the jetty is increasingly encouragedtoward the outer end to eliminate cans-- ing movement of thecurrents around the cadet as the jetty with accelerated velocity and thereby eliminate the objectionable scouring at the outer end and on the lee side.

Byreferringtong.4,itwfllbeseenthat with applicant's type of jetty II, that whentheeil windistravelinginanobliquedireetiontoward indicated, approximately parallel to the shore.

changingdirectionandtravelimat tangles tothesidesofthejettyandaround tbeouter succusivejetiy. 'Iheresultwillbeagradhalla.

, extending outwardly extending outwardly at an slowing down of the littoral currents to cause -a gradual deposit of sand and the formation of an ever widening beach composed of fine ma-' terial, as indicated by the numeral 6 wherein the angle of the beach is relativelyflat, and wherein the tendency for the beach to concentrate directly adjacent the sides of the jetty is minimized.

It will further be seen that with the present invention, the area of new land formed will be much greater per foot of jetty than would occur with an ordinary type of construction, and that the sloped sides of the jetty shown in the cross sections tends to nullify wave action and to reduce the energy of the littoral currents.

Although only one form of the invention has been shown and described, it is to be understood that various changes and modifications may be made, and that allot such changes are contemplated as may come within the scope of the claims.

What I claim is:

1. A jetty comprising an elongated wall of rock at an angle to the shore. said rock being laid in relatively loose iormation to render the jetty permeable.

2. A jetty comprising an elongated wall 0! rock said rock being so laid as to, render the jetty increasingly permeable outwardly.

extending outwardly at an angle to the shore, said rock being laid to provide sloping sides and in relatively loose formation to render the jetty permeable I 4. A. jetty for use on a lake .shore bordered by a hillside or the like, wall extending wardly into the water'a substantial distance at an angle to said hillside, wall extending into the water being formed oi rock laid in relatively loose formation to render the wall permeable.

5. A jetty ior use on a lake shore bordered by a hillside or the like, comprising. an elongated wall extending an angle to said hillside, the-portion oi said wall extending into the water beingiormed 0! rock laid in relatively loose formation to render the wall being formed of individual angle to the shore,

from adjacent said hillside outwardly into the water a substantial distance at le, the major portion oi said wall being above the water level, and the extreme outer end being submerged.

B. A jetty comprising an elongated wall extending outwardly at an angle to the shore, said wall 5 having outwardly increasing permeability to partially obstruct littoral currents and thereby cause a gradual decrease in the velocity 0! said currents and the deposit oi beach building material. 10

7. A jetty comprising an elongated wall extending outwardly ,at an angle to the shore. said elements positioned relative to one another with increasing looseness outwardly toprovide for outwardly in- 5 and said elements bein in traveling .through i the struct. littoral currents and thereby cause a grad- 0 um decrease in the velocity of said currents and the deposit oi beach building material.

8. A jetty comprising an elongated wall expasses the wall and thereby render the jetty ermeable,

and the elements being further so positioned relative to one another as to provide a wall havo ing substantial width wherein the water passes in an indirect course in traveling through the wall to partially obstruct littoral currents and thereby cause a gradual decrease in the velocity of said currents and the "deposit of beach build 5 ing material. 1 9. A jetty comprising an elongated wall extending outwardly at an angle to the shore. said wall being formed of superimposed rows oi elements positioned with increasing leosenea! out- 40 wardly to provide for outwardly increasing permeability. and said elements being laid to provides wall having substantial width wherein the water passesin an indirect. tortuous course in. traveling the wall to artially obstruct g littoral currents and thereby cause agrodual decreaseintheyelocityotsaideurrmtsandtbe deposit oi beach buildin SYDNEY MI. WOOD. 

